Stators in AC & DC electric motors are generally made of silicon steel sheets. With the extension of application fields, motors are being developed in a direction of high speed and high power. The electromagnetic characteristics of silicon steel sheets limit their use to a maximum alternative frequency of about 300 HZ. Above this frequency, iron loss will make silicon steel sheets generate heat, dramatically impairing efficiency and often hunting often out the coils.
Iron-based amorphous material has excellent high-frequency characteristics, extremely low iron loss and desirable additivity, making its application range increasingly wide. In the aspect of high power, it shows a trend of replacing ferrite. However, the extreme thinness of the amorphous strip and its sensitivity to temperature and stress present challenges to the machining process when iron-based amorphous material is used to manufacture motor rotors and stators.
As iron-based amorphous material is normally only 20-26 μm thick, a small slip in shaping, heat treatment, bonding or other processes will damage the materials electromagnetic properties. For example, during electrical discharge machining, local “spark” temperature makes amorphous material “recrystallized”, thereby losing amorphous characteristics and causing machining failure.
The stress generated from eating and bonding is also an important threat to amorphous material. Likewise, a tiny mistake in the heat treatment process may also result in failure.
At present, iron-based amorphous material is successfully applied in a minority of rotors but no application in stators with a complex shape has been reported. Therefore, what is needed is a novel, iron-based amorphous material for complex-shaped and conventional stators.